The present disclosure relates to a display panel capable of controlling the orientation of liquid crystal molecules with a horizontal electric field, and a method of manufacturing such a display panel. The present disclosure is also concerned with a display device and an electronic apparatus which incorporate the above display panel.
At present, liquid crystal panels are widely used in mobile devices such as mobile phones and laptop personal computers. One type of liquid crystal panels that has heretofore been popular in the art is a vertical-electric-field liquid crystal panel exemplified by liquid crystal panel using a TN (Twisted Nematic) liquid crystal. The vertical-electric-field liquid crystal panel displays an image based on a change in the light transmittance of the panel which depends on the orientation of liquid crystal molecules when the liquid crystal molecules are oriented in the direction of an electric field that is applied perpendicular to the substrate of the panel.
However, the vertical-electric-field liquid crystal panel has been problematic in that it provides a small viewing angle because the observer sees liquid crystal molecules in different directions if they see the display surface of the liquid crystal panel at different angles. One solution to the problem has been proposed by a horizontal-electric-field liquid crystal panel as disclosed in Japanese Patent Laid-Open No. 2002-182230.
The horizontal-electric-field liquid crystal panel displays an image based on a change in the light transmittance of the panel which depends on the rotation of liquid crystal molecules when the liquid crystal molecules are rotated in a plane parallel to the surface of the substrate of the panel by an electric field that is applied parallel to the substrate. The horizontal-electric-field liquid crystal panel provides a wide viewing angle because the observer sees liquid crystal molecules in one direction even if they see the display surface of the liquid crystal panel at different angles.
Horizontal electric fields may be generated by an FFS (Fringe Field Switching) mode (Japanese Patent Laid-Open Nos. 2008-52161 and 2008-165230 (hereinafter referred to as Patent Documents 1 and 2)) and an IPS (In-Plane Switching) mode. According to the latter IPS mode, an electric field is mainly generated only in a horizontal direction parallel to the substrate surface, but is less liable to be generated in a region above pixel electrodes. Therefore, since only liquid crystal molecules that are present between adjacent pixel electrodes are driven, the liquid crystal panel tends to have a low aperture ratio. According to the former FFS mode, a horizontal electric field is generated between pixel electrodes, and a horizontal oblique electric field or a parabolic electric field is generated in a region above pixel electrodes. Therefore, not only liquid crystal molecules that are present between adjacent pixel electrodes, but also liquid crystal molecules that are present above pixel electrodes are sufficiently driven. Consequently, the FFS mode provides a higher aperture ratio than the IPS mode.